Without limiting the scope of the invention, its background is described in connection with current methods of etching barium strontium titanate, as an example.
Barium strontium titanate (BaSrTiO.sub.3, hereafter abbreviated BST), because of its electrical and mechanical properties, has found many uses in the field of electronics. The very high dielectric constant exhibited by BST makes it useful as the dielectric material in capacitors. BST also has a positive temperature coefficient of electrical resistance, which allows devices to be made which protect electrical motors from damage due to over-current conditions. Microminiature structures which incorporate BST are being used to sense infrared radiation, obviating the need for bandgap detector materials which require cryogenic cooling to sense the infrared.
Materials such as BST are often etched during the fabrication of the electrical devices which exploit their beneficial properties. A method used to etch BST should generally do so without introducing damage which would unacceptably change the properties of the material on which the function of the eventual devices depends. In addition, an anisotropic etch method is usually desired so that detail in the etch mask pattern is preserved. Contamination of the BST material (and/or nearby materials) by the etch method usually cannot be tolerated.
Heretofore, in this field, BST has been etched by isotropic wet etching, ionmilling, plasma etching or laser scribing. Laser scribing is a method wherein selected portions of the material are damaged and weakened by exposure to intense laser radiation and then removed.